<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>响应式布局</title>
  <style type="text/css">
      @media only screen and (max-width: 374px) {
          /* iphone5 或者更小的尺寸，以 iphone5 的宽度（320px）比例设置 font-size */
          html {
              font-size: 86px;
          }
      }
      @media only screen and (min-width: 375px) and (max-width: 413px) {
          /* iphone6/7/8 和 iphone x */
          html {
              font-size: 100px;
          }
      }
      @media only screen and (min-width: 414px) {
          /* iphone6p 或者更大的尺寸，以 iphone6p 的宽度（414px）比例设置 font-size */
          html {
              font-size: 110px;
          }
      }

      body {
          font-size: 0.16rem;
      }
      #div1 {
          width: 1rem;
          background-color: #ccc;
      }

  </style>
</head>
<body>
<div id="div1">
  this is div
</div>
</body>
</html>
